# Build an Agent

> Spin up an autonomous agent on the agent-runtime satellite — try templates first, custom build only if no fit.

- **Kind**: Shell tool
- **Category**: engineering
- **Owner**: Sentinel (/sentinel)
- **Default model**: sonnet
- **Cost class**: standard (Sonnet-class model. Default for most skills.)
- **Turn budget**: 12
- **Execution**: synchronous (result lands in the same turn)
- **Canonical URL**: https://app.51ultron.com/docs/skills/build-agent

## What it does

Two-phase agent builder. Phase 1: agent templates lists 25 curated patterns (support, research, digest, review, status-page-monitor, etc.); if any match the user's goal, use it. Phase 2 (fallback): follows build-agent/SKILL.md to scaffold from scratch with the right tool palette (compose-tools/SKILL.md keeps the integration list minimum-viable to avoid model confusion). Returns the agent id and an inspect URL.

## When to use this

- user wants an autonomous agent that runs on a schedule
- user says 'build me a support bot' / 'I want an agent that monitors X' / 'set up an automation that runs every morning'
- user has a recurring workflow to automate

## When NOT to use this

- user wants a one-off task (no scheduling, no autonomy) → use whatever tool fits
- user wants to inspect an EXISTING agent → run `agent show <id>` directly

## Example prompts

- `build me a customer-support agent that watches new tickets`
- `set up an agent that gives me a daily digest of competitor moves`
- `I want an agent that monitors my status page and alerts on outages`
- `create an agent that reviews PRs`

## Inputs

- **goal**: what the agent should do, in one sentence
- **schedule**: optional cron or natural-language frequency

## Output

Agent id, the chosen template (or 'custom'), and the agent-runtime inspect URL.

## Tools used

`shell_exec`

## Execution template

Shell tools dispatch through `shell_exec` with the following command template:

```bash
agent templates; if match: agent create from template; else follow build-agent/SKILL.md per compose-tools rules
```

## Tags

`engineering`, `agent`, `automation`

## Keywords

agent, autonomous, bot, automation, schedule, recurring, template